Hi all, hope this post is in the correct section, this is my first post on the Sub Committee's site, i'm not new to the building of rc subs and have scratch built my own dynamic divers in the past, however I now wish to progress onto static divers but am having some difficulty in sourcing components for the construction of wtc's, can any one help with a list of suppliers, for these components and any others that may be usefull.thanks Jim

I like the pressure pumped system but this does need the right pump - e.g a "gear" pump able to produce about 2 bars. (Red cased Graupner pump sold as a fuel pump to our flying friends does the trick.)

I like the pressure pumped system but this does need the right pump - e.g a "gear" pump able to produce about 2 bars. (Red cased Graupner pump sold as a fuel pump to our flying friends does the trick.)

That's a very generic statement on the Engel site, a 750ml tank may well be enough for many models, but others may need more, some may need less.

Generally speaking, the older boats tend to have higher freeboard, so you will very likely need a larger tank to sink these beasts.

Also how is the boat being built- wet hull or dry hull?

Does any of the watertight enclosure, be it box, cylinder whatever project above the surfaced waterline?

The way to size the ballast tank has been well documented on this site in the past. Do a little searching and you'll find some answers.

Piston tanks offer a very precise method of ballasting a submarine, however if you use a single tank, you will end up with a shifting C.G as you fill and empty the tank. The longer and slimmer the tank, the worse the problem becomes.

In the real world this isn't as big an issue as you think, as submarines tend to adopt a nose down/nose up attitude as they submerge/surface anyway.

However one way of overcoming this is to use twin tanks that work in opposite directions.

Waterpump systems work well enough, and are very cheap to build and operate. One problem I have noticed in the Sheerline models, is inadequate baffling of the ballast tank.